when charles darwin set sail on his five year journey on the hms beagle most scientists at the time thought that

Ten percent of energy is transferred from sun to the level indicated.

The casefor proofs

Ibelieve the answer is relative humidity  because it makes more sense that way. solar flares usually occur in space it doesn't affect the earth, well it could but it wont make a significant damage.  latitude is land it doesnt do anything. prevailing winds, i dont know the correct meaning for this but i doubt that affects the land so it has to be relative humidity.